A Method for Improving the Sensitivity Based on Adaptive Compensation In MPI

In the Magnetic particle imaging (MPI) system, due to the existence of the feed-through signal caused by the mutual inductance between the excitation coil and detection coil, the fundamental frequency component of the particle signal is polluted and cannot be used. However, the fundamental frequency component is the largest energy proportion of the particle signal, the absence of the fundamental frequency component will reduce the signal-to-noise ratio of the signal, resulting in limited sensitivity of MPI devices. In this study, we proposed a method to which can adjust the phase of the compensated signal quickly accurately and adaptively according to the actual attenuation degree of feed-through signal based on FPGA (Field-Programmable Gate Array) and analog differential circuits. It avoids the phase shift between the compensation signal and feed-through signal caused by irrational factors such as limited DAC conversion rate and signal propagation path delay, and does not require multiple iterations to obtain the phase information of the compensation signal, improving attenuation effect and stability, and simplifying the compensation process. As a result, the experimental results show that this method can retain the complete particle signal and improve the signal-to-noise ratio of the particle signal and the sensitivity of the MPI device relative to the analog filtering method.